Electric discharge apparatus



' high temperatures to visions both for rapidly 59 the cylinders closed by insulating disk 5 into 1 3 in rod'or Patented May 31, 1932 y UNIVILDV STATESA PATENT 4ol-"Flcn Galenus C. vsiriana-'or iunnrom), MassACHUSETTs, ASSIGNCR To RAYTHEON INC., or f CAMBRIDGE, MASSACHUSETTS,- A CORPORATION or MASSACHUSETTS ELECTRIC DISCHARGE APPARATUS Application led June 13,

The present invention relates generally to the art of tube manufacture and in particular to an improved process of making a glass seal and shielding electrodes from ionic bombardment.

Considerablediiiiculty has heretofore attended fusing of the envelop material about the upstanding conductors notwithstanding the universal employment for Sealing-in wires and. electrodes, of 'metal having a coelicient of expansion 'commensurate with the surrounding glass. Moreover, the materials commonly employed for shielding e. g., lava,

are of more orlessbulky form 'and susceptible to fracture.

The difculties are enhanced in modern apparatus due to the .extraordinary increase in power nous7 handled by a single unit causing be localized about the junction of the metal and glassz and in space current apparatus of the gaseous type, there is ever present incessant bombardment by stray ions in the region of the stem. These factors inevitably tend to reduce the life of the device in question.

With these features in mind, Il propose to provide a novel form ofstem having prodissipatingthe heat. gathered yabout the lower extremities ofthe electrodes and also for preventing deleterious electrical action taking place at these points.'` Other objects are to assure an effectivel seal wherein the actual place of sealing on'the sealing-in wire comes in a region where the glass is relatively cool;/to improve the man-f' ner of supporting the. electrodes. from the Stem and in general, the art of electrical conj duction. v

The accompanying'drawing illustrates a form of tube lembodying the'new features of the present invention. This embodiment ex-l emplifies an envelop 1 of glass, quartz or the like containing a gas preferably ofthe mon? atomic group, e.` g. helium at a pressure ofv several mm. Hg, hollow cathode 2 and anodes' pgfor'm, each of refractory ma- 'se comprising metallic cylinder suitable compound to `the',en

The bottom of terial and a. 4 secured byvelop in the usual manner.

1927. serial No. 198,:399.

suitable shape such as conical) closed at one end and the lower part 8 a cover fitting the open end of the cylinder and secured thereto. In the cover there are apertures or openings through which the anodes may actually project or be merely presented to the interior of the cathode. In order to minimize the internal losses of the device I prefer to coat the inner or active portion ofthe cathode with a Substance as al'kali or earth alkali to increase the emission or I may polish the surfacewith a view toward reducing absorption of heat. The cathode is supported at diametral points by two stili wires anchored to the stem or in any other suitable manner. As shown, concentric with each sealing-in wire 9, in contradistinction to a leading-in conductor, there is a hole or cavity sunk to anv appreciable depth and containing an amount of refractoryl insulating material l0 .preferably granulated or nely divided form, e. g. magnesium oxide. Numeral ll indicates a metal cylinder or shield individual to each anode preferably of nickel and drawn down to a a snug lit in the' outercavities for sealing.

The upper or flared ends, of theupstanding cylinders extend through the apertures in the preferably equidis-v periphery of the shown, the device operates upon the ioniza- Y tion principle as a glow;y discharge,`the active region being confined to the enclosed cathode chamber. y

From the' foregoing it will bey smaller diameter at its lower part to furnishy the apertures,

y evident imc among the functions of the 'comminuted .ferred and distributed. To au insulating material are those of providing long creepage paths between the sealing-in wires and adjacent shields; also of preventing direct contact between the glass and wires at the upper and more heated portion of the press. The lengthening of the creepage paths is beneficial in minimizing deleterious electrical effects taking place at the upper terminating surface of the reentrant stem; moreover, only that portion of the press which is relatively cool actually touches the metal conductors by reason of the glass seal. The shields or cylinders not only discourage ionization at the base of the anodes but also tend to equalize the -heat stress throughout the stem by presenting a relativel large contacting surface to the periphery o each cavity to which heat derived from discharge may be readily transent the desirable features of the stem, may employ copper or other metal of relatively high thermal conductivity for leading-in wire 12 from the connector plugs as far as the envelop, offering additional means of egress for the heat stored in the glass.

While I have described my invention in connection with particular apparatus, it is apparent that its application is quite general and may be employed to advantage with all forms of glow discharge, e. g. amplifiers, oscillators, rectifiers and the like. The invention has also marked utility in the lamp art, the shields being placed about the lower portions of the filament; in case the gas is omitted, the spacing between the anodes, shields and cathode should be changed accordingly.

I claim:

1. A gaseous conduction rectifier having a plurality of electrodes, vone of which is a cold cathode, a press of insulating material, conductors sealed therein and extending therethrough, said electrodes connected to said conductors at one end thereof, said press having enlarged openings at the endA adjacent the electrodes, each opening surrounding a conductor, a. metallic shield embedded in certain of said openings, said shield extending from Vsaid openings up to the electrodes and surrounding the conductor and electrode.

2. A gaseous conduction rectifier havinga plurality of electrodes including a cold cathode, a glass press, conductors extending therethrough, and sealed therein, said press having enlarged openings at one end surrounding each of said conductors, said electrodes connected to said conductors, and shields for certain of said conductors embedded in the openings and extending to said electrodes, said shields surrounding said conductors and said electrodes and a acking of comminuted material in seid enarged openings.

3. A gaseous conduction recter compris extending ing an envelope containing a rareied atmosphere, a plurality of electrodes, one of which is a cold cathode, a press therein, conductors through said press and sealed therein, said press having enlarged openings around each of said conductors at one endV thereof, said electrodes connected to the conductors, certain of said conductors having metallicshields embedded in said enlarged openings and vextending along said conductors to said electrodes, said shields surrounding saidy conductor and electrodes along the entire length of said shield, said shield having a spacing of theorder of the mean free path of the atmosphere within said envelope from said electrodes.

4. A gaseous conduction rectifier comprising. an evacuated envelope containing a. rarefied atmosphere, a plurality of electrodes, one of which is a cold cathode a glass press within said container and having conductors extending therethrough and sealed therein, said electrodes within said envelope connected to said conductors, one of said electrodes substantially enclosing the remaining electrodes, metallic shields around said remaining electrodes, said shields surrounding said remaining electrodes and spaced from adjacent electrodes by a distance comparable to the mean free path of the atmosphere within said envelope, said shields extending from within the enclosing electrode to without it.

`5. A' gaseous conduction rectifier comprising an evacuated envelope containing a rarefied atmosphere, a plurality of electrodes including a cold cathode a glass press therein, and having conductors extending therethrough and sealed therein, said electrodes connected to said conductors, one electrode substantially surrounding the other electrodes, said other electrodes having metallic shields surrounding them, each of said metallic shields being aced a distance comparable to the mean ree path of the atmosphere within said envelope from adjacent electrodes, each of said shields extending from within said enclosing electrode to without it.

6. An electrical device comprising an evacdivided insulating material packed around the each conductor at a press. v 7. An electrical device comprising an evacuated envelope containing a rarefled atmosphere, a glass press therein, conductors eX- tending therethrough and sealed therein, electrodes connected to said conductors, one of said electrodes enclosing the remaining electrodes, each of said remaining electrodes having a shield embeddedl in the glass press portion thereof Within and surrounding the corresponding conductor and electrode, said shields surrounding said conductor and electrodes and being spaced from adjacent electrodes a distanceJ comparable to the mean free path of the atmosphere Within said envelope and a finely divided insulating material packed around each conductor surrounded by said shields at a portion of said conductor .Within the press.

Signed by me at Cambridge, Massachusetts, this 6th day of June, 1927.

- CHARLES G. SMITH. 

